The present invention relates to a valve device and a liquid ejection apparatus.
Up to now, an ink jet type recording apparatus has been widely used as a liquid ejection apparatus which ejects a fluid toward a target. In detail, this ink jet type recording apparatus comprises a carriage, a recording head mounted in this carriage, and an ink cartridge that stores the ink, which is a fluid. Printing is performed on a recording medium by ejecting ink supplied to a recording head from the ink cartridge from a nozzle formed in this recording head with the carriage moving relatively to the recording media, such as paper.
As such an ink jet type recording apparatus, there is an “off-carriage” type where an ink cartridge is not mounted in the carriage so as to decrease the load on the carriage or to miniaturize or thin an apparatus. In this off-carriage type of ink jet type recording apparatus, ink in an ink cartridge is supplied to the recording head through a flexible ink supply tube.
Generally, when replacing an ink cartridge etc., the ink cartridge is removed from an ink supply tube. Nevertheless, in a detached state, since an ink passage from the ink supply tube to the recording head is opened to the air, there is a possibility that the ink which remains in the ink passage will leak to the outside from the ink passage, and dry.
It is then conceivable to provide a valve device in the middle of the ink passage etc., to prevent leakage of the ink from the ink passage and drying of the ink by closing the valve device at the time of replacing the ink cartridge, and etc.
A valve device applicable as the valve device as described above is disclosed in Japanese Laid-Open Patent Publication No. 2000-81162. The valve device disclosed in this publication comprises a valve body having an ink passage, and a valve member. The valve body has a valve seat which is located in the ink passage. The ink passage is opened and closed by the valve member abutting on and separating from the valve seat. The valve body comprises a film-like member which can be elastically deformed along a movement direction for ink, and the valve member is fixed to this film-like member.
The valve body is formed of a magnetic material which has a high magnetic permeability, and an excitation coil is wound around the valve body. The valve member is made of a magnetic material or a permanent magnet. In connection with the excitation coil being excited or de-excited, the valve member separates from or abuts on the valve seat, and hence, the ink passage is opened and closed thereby.
The valve device in the above-mentioned publication is constructed by an electromagnetic actuator which drives the valve member by using the excitation coil provided around the valve body. The adoption of such an electromagnetic actuator causes complication and upsizing of the valve device. In addition, since the valve member cannot be driven while an ink jet type recording apparatus is not powered, it is inferior in the degree of freedom for driving of the valve member. Furthermore, in order to achieve electromagnetic driving, it is necessary to form the valve body, which functions as a core of the excitation coil, with a magnetic material, and hence, a material which can be used as the valve body is limited. This becomes a cause for limiting the degree of freedom in the design of the valve device.
On the other hand, Japanese Laid-Open Patent Publication No. 5-263960 discloses a valve device which can decrease the noise at the time of opening and closing the valve member. The valve device disclosed in this Japanese Laid-Open Patent Publication No. 5-263960, as well as the valve device disclosed in the above-mentioned Japanese Laid-Open Patent Publication No. 2000-81162, is also constructed by an electromagnetic actuator. Therefore, also when the valve device in this Japanese Laid-Open Patent Publication No. 5-263960 is applied to an ink jet type recording apparatus, the same problem as the valve device in Japanese Laid-Open Patent Publication No. 2000-81162 arises.